Polarization-Independent Multiple Fano Resonances in Plasmonic Nonamers for Multimode-Matching Enhanced Multiband Second-Harmonic Generation
Polarization-Independent Multiple Fano Resonances in Plasmonic Nonamers for Multimode-Matching Enhanced Multiband Second-Harmonic Generation
复制标题
等离激元九聚体中与偏振无关的多重 Fano 共振，用于多模匹配增强型多频带二次谐波生成
DOI：
10.1021/acsnano.5b06956
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发表时间：
2016-01-01
期刊：
影响因子：
17.1
通讯作者：
Lei, Dang Yuan
中科院分区：
文献类型：
--
作者：
Liu, Shao-Ding;Leong, Eunice Sok Ping;Lei, Dang Yuan
由金属纳米粒子组成的等离子体低聚物是一类最有希望产生Fano共振的平台之一，它具有前所未有的光学性质，可以增强各种线性和非线性光学过程。为了有效地在多个波长产生二次谐波发射，设计一种同时具有多个Fano共振光谱匹配基波激发波长和多个等离子体激元共振模式与谐波波长一致的等离子体低聚物是至关重要的。到目前为止，实现这种等离子体低聚物仍然是一个挑战。本研究从理论和实验两个方面证明了由八个纳米棒包围的金纳米十字组成的等离子体九聚体在近红外区同时存在多个与偏振无关的Fano共振，在可见光光谱中存在多个高阶等离子体激元共振。由于Fano共振对非线性激发源的相干放大和高阶模的有效散射增强输出耦合，使得非线性激发子在多个光谱波段的二次谐波发射显著增加，并且其光谱位置和辐射模式可以通过容易地调节周围纳米棒的长度来灵活控制。这些结果为实现超快多通道非线性光电子器件提供了重要的启示。
Plasmonic oligomers composed of metallic nanoparticles are one class of the most promising platforms for generating Fano resonances with unprecedented optical properties for enhancing various linear and nonlinear optical processes. For efficient generation of second-harmonic emissions at multiple wavelength bands, it is critical to design a plasmonic oligomer concurrently having multiple Fano resonances spectrally matching the fundamental excitation wavelengths and multiple plasmon resonance modes coinciding with the harmonic wavelengths. Thus far, the realization of such a plasmonic oligomer remains a challenge. This study demonstrates both theoretically and experimentally that a plasmonic nonamer consisting of a gold nanocross surrounded by eight nanorods simultaneously sustains multiple polarization-independent Fano resonances in the near-infrared region and several higher-order plasmon resonances in the visible spectrum. Due to coherent amplification of the nonlinear excitation sources by the Fano resonances and efficient scattering-enhanced outcoupling by the higher-order modes, the second-harmonic emission of the nonamer is significantly increased at multiple spectral bands, and their spectral positions and radiation patterns can be flexibly manipulated by easily tuning the length of the surrounding nanorods in the nonamer. These results provide us with important implications for realizing ultrafast multichannel nonlinear optoelectronic devices.